NEW YORK (Reuters) - JPMorgan Chase & Co, looking to stem falling revenue in its mortgage business as fewer Americans refinance, is increasingly buying loans from smaller lenders, a practice that competitors including Bank of America view as risky. In the first half of 2015, the bank bought 62 percent of the $58 billion in home loans it added to its books, compared with 56 percent in 2014 and 37 percent in 2011.